The present invention relates to a method of changing the high speed reel control transport and the low speed capstan control transport in tape transport control of a magnetic recording playback apparatus or the like and an apparatus using the method.
As an apparatus in the prior art, for example, as described in Japanese patent application laid-open No. 198460/1986, in order to drive a tape at high speed, a reel driving means is disclosed where the tape is transported at high speed and constant speed in capstan-less state. That is, as a method of making the tape speed constant, the tape is grasped by a capstan and a pinch roller and the rotational speed of the capstan is made constant thereby the tape speed is made constant. However, if the tape speed remaining intact is made high speed, it is difficult in the mechanism of the driving apparatus and the tape is liable to be damaged. Consequently, a method of making the tape speed constant in capstan-less state has been used. In this method, however, the stable transport in capstan-less state becomes difficult at low speed on the contrary. Consequently, after all, two-mode system is required where the low speed transport by capstan driving and the high speed transport by reel driving are specifically distinguished with discontinuity.
Speaking it more specifically, in the prior art as above described, it is difficult that the capstan driving mode at low speed transport (low speed capstan driving mode or referred to simply as capstan driving mode or only as low speed driving mode) and the reel driving mode at high speed transport (high speed reel driving mode or referred to simply as reel driving mode or only as high speed driving mode) are covered from high speed to low speed continuously. That is, particularly during transport from the high speed transport (reel driving) to the low speed transport (capstan driving), the pinch roller must be pressed against the capstan in the tape transport state. In this case, due to the speed error between the tape transport speed and the capstan rotational speed, abnormal tension is applied to the tape and a problem of damage of the tape may be produced. Consequently, it is difficult to realize the continuous covering of both modes.
Therefore in the apparatus in the prior art, in the transferring from the high speed transport (high speed mode) to the low speed transport (low speed mode), such discontinuous operation is inevitable that after transport of the tape is once stopped, the pinch roller is pressed and then the starting to the low speed transport is performed (moving to the low speed transport) and therefore the operation becomes difficult. Also in the above-mentioned apparatus, since the stop state of the tape is once entered so as to press the pinch roller, time is required until attaining the normal capstan driving state. For example, in heading of the tape (positioning at prescribed portion), troublesomeness in the operation and the obstacle in the high speed operation are inevitable.